Currently, glue-laminated beams (“gluelam”) in Europe are mostly produced according to DIN 1052:2008 (German standard) or DIN EN 14080: 2013-09 (harmonized European standard). The beams are built up with visually graded or machine graded boards, which are produced and kiln-dried in sawmills in the traditional way.
The gluelam producer takes these boards as raw material, grades them and produces the required lamellae by cutting out defects (e.g. knots) and finger-jointing the pieces together. After the finger-jointed lamellae have been planed, glue is applied and the beam is formed by gluing the lamellae together. The final steps may comprise planing the beam, removing optical defects, packaging and loading it.
Hence, traditionally, timber is sawn into planks or lamellae according to the scheme depicted in FIG. 1 of U.S. Pat. No. 5,816,015, which discloses alternative methods of forming wood beams by laminating together a plurality of planks or lamellae.
EP1277552A2 discloses a similar method of forming a wood beam by cutting a round piece of timber into a plurality of strips having a trapezoidal cross section and laminating together the pieces thus formed into a beam.
U.S. Pat. No. 4,122,878 discloses a method of converting balsa wood of relatively small diameter into panels.
There is still a need to provide improved use of the timber raw material, as well as a need for beams having improved strength and/or reduced variation in strength between different beams.